From: Nicolas Richard <youngfrog@members.fsf.org>
Date: Fri, 19 Jun 2015 14:57:26 +0000 (+0200)
Subject: Fixes: debbugs:20832
X-Git-Tag: emacs-25.0.90~1699^2~1
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=b9f02cf;p=emacs.git

Fixes: debbugs:20832

* lisp/calendar/todo-mode.el (todo-show): Signal an error
if buffer for adding new todo file is empty but modified.
---

diff --git a/lisp/calendar/todo-mode.el b/lisp/calendar/todo-mode.el
index dcc960fb9bf..6e975249a3f 100644
--- a/lisp/calendar/todo-mode.el
+++ b/lisp/calendar/todo-mode.el
@@ -743,6 +743,11 @@ corresponding todo file, displaying the corresponding category."
 	    (setq todo-category-number (todo-category-number cat)))
 	  ;; If this is a new todo file, add its first category.
 	  (when (zerop (buffer-size))
+            ;; Don't confuse an erased buffer with a fresh buffer for
+            ;; adding a new todo file -- it might have been erased by
+            ;; mistake or due to a bug (e.g. Bug#20832).
+            (when (buffer-modified-p)
+              (error "Buffer is empty but modified, please report a bug"))
 	    (let (cat-added)
 	      (unwind-protect
 		  (setq todo-category-number